It is known to provide a main large diameter pipe fed with slurry made of mine residues and having a series of small diameter spigots, which can be successively closed or opened manually on one side.
The slurry is discharged at selected points on the ground for dyke building and when the slurry pile is sufficiently high at one spigot the latter is closed and opened again after extending the branch to an adjacent location. Once a certain area has been filled with the slurry, the branches are disconnected from the main pipe and again have to be connected after moving the entire assembly to another site.
This system has several disadvantages. It requires a large pumping capacity because of the resistance to the flow of slurry through the small diameter spigots. It is labor intensive since the branches have to be extended continuously. The branches are connected to and disconnected from the main pipe each time the system is moved to another site. The main drawback is the fact that the starter dyke which must be mechanically built to form an abutment for the succeeding deposition of the slurry must be quite high and wide requiring several weeks of work by mechanical earth movers such as bulldozers to place the required volume for the starter dyke. This represents a major portion of the cost of building or increasing the height of the retaining dyke. In addition, this system does not lend itself to general tailings disposal.
It is also known that for small smaller slurry flow requirements to provide a pipe with holes in the bottom suspended on wood racks. This method allows the deposition of the coarse portion of the tailings through the holes until they are successively obstructed. A length of this perforated pipe is installed perpendicular to the starter dyke.
This system has several disadvantages. It can only be used for general tailings disposal and is not efficient (in many cases inadequate) for dyke construction because it does not allow for a uniform distribution of the slurry material from the beginning to the end of the pipe, hence the deposition angle formed at each successive hole becomes flatter and flatter. It does not allow for control of the slurry composition.